1. Field of Invention
The present invention relates to seatbelt retractors. In particular, the present invention relates to an electrical seatbelt retractor including a motor for driving a spool to rotate.
2. Description of the Related Art
A seatbelt retractor functions to spool a seatbelt drawn out too far when a passenger is seated, draws the seatbelt, and couples a tongue of the seatbelt with a buckle device.
Certain known seatbelt retractors use a return spring to wrap the seatbelt around a spool. When fastening the seatbelt, a passenger draws the seatbelt which is urged by the return spring, couples the tongue with a buckle, and releases the seatbelt. The seatbelt drawn out too far is retracted by a return spring force until a webbing of the seatbelt fits the passenger. Such a seatbelt retractor must satisfy the following conditions: (1) the excess webbing drawn out must be reliably spooled until the seatbelt fits the passenger, and when the passenger stops fastening the seatbelt, the webbing drawn out is reliably retracted by the seatbelt retractors; and, (2) the seatbelt is fastened so that the passenger does not have the sensation of being excessively restrained at the chest and the like.
However, a problem has been found in retractors using only an urging force of a return spring. When a return spring having a small urging force is used so as to reduce the oppressing sensation at the chest of the passenger by fastening the seatbelt, the retracting force for spooling (retracting) the webbing decreases, thereby reducing the performance in operation and retraction. On the other hand, when a return spring having a large urging force is used so as to secure a sufficient retracting force for spooling the webbing, the sensation of the passenger of being pressed at the chest when fastening the seatbelt increases excessively.
Accordingly, an object of the present invention is to provide a seatbelt retractor in which it is not necessary to wire lead wires in a cover included in the seatbelt retractor.
Another object of the present invention is to provide a seatbelt retractor in which a circuit board and the like can be positioned accurately.
Still another object of the present invention is to provide a seatbelt retractor in which mechanical components can be mounted on a retainer after a circuit board is mounted on the retainer, without directly touching the circuit board previously mounted.
According to the present invention, a seatbelt retractor, which includes a spool for spooling a webbing, a motor for driving the spool to rotate in a direction to spool the webbing, and a power transmission structure for transmitting the rotational driving force of the motor to the spool, comprises a circuit board provided with a circuit for controlling the rotation of the motor, and connectors for feeding current; a rotational direction determining unit for determining the rotational direction of the spool; and a retainer mounted with the motor, the power transmission structure, the circuit board, and the rotational direction determining unit. The tabular retainer is provided at a surface thereof with the power transmission structure, the circuit board, and the rotational direction determining unit. An outer cover is mounted on the retainer so as to cover the surface of the retainer including the power transmission structure, the circuit board, and the rotational direction determining unit.
In the seatbelt retractor, the circuit board is provided with the connectors, whereby wiring of lead wires in a cover can be eliminated by mounting the circuit board on the retainer so that the connectors extend toward the outside of the cover.
When the rotational direction determining unit includes a limit switch, lead wires of the limit switch can be eliminated by providing the limit switch on the circuit board. By mounting the limit switch on the circuit board via a resilient member such as a coil spring, a large stress applied to the limit switch can be suppressed.
According to the present invention, an inner cover for covering the circuit board may be provided, which is covered by the outer cover. With this arrangement, when mechanical components are mounted after the circuit board is mounted on the retainer, the circuit board is prevented from being touched by hands, tools, mechanical components, and the like because the circuit board is covered by the inner cover.
In this case, connector-passing openings are preferably provided in the inner cover so that the connectors extending from an edge of the circuit board pass through the connector-passing openings and extend toward the outside of the inner cover.
According to the present invention, the circuit board may be either anchored to a groove formed in the inner cover or be clamped by the retainer and the inner cover, whereby the circuit board can be positioned accurately.